The phenomenon of 'core groups' of gonorrhea, in which a small proportion of individuals account for a large proportion of infections, has been described for urban populations. The presence of core groups, and the epidemiology of sexually transmitted diseases (STDs) in general is virtually unstudied in rural populations. We propose a multidisciplinary epidemiological study of infections with N. gonorrhoeae, C. trachomatis, and T. pallidum in the rural county of Wilson, North Carolina. Our aims are to 1) perform an ethnographic study of individuals at high risk of STDs; 2) enroll and follow a cohort of clients from a public health (PH) STD clinic; and 3) develop and evaluate a community-based intervention to prevent STDs. The ethnographic study will consist of 50 2-3 hour interviews with high risk individuals in Wilson, observations in social gathering sites, and focus group discussions pertaining to DTD risks and prevention. These qualitative data will identify relevant STD-related behaviors to include in the cohort study, and provide information needed to tailor the proposed intervention to Wilson County. The cohort study will enroll 3041 STD patients in the PH clinic during an 18 month period. Data collected will include clinical specimens for STDs, a self- administered questionnaire, medical record abstraction and, for a sample of patients, an interview-based questionnaire. Repeat data collection will be performed on cohort members identified with a symptomatic STD (thus 'cases') during an 18-month follow-up period (n=395). The risk of becoming a case will be compared among different levels of the independent variables. The cohort study is complemented with 1) a case- control study nested within the cohort to compare changes in independent factors with those in cases and estimate the occurrence f asymptomatic infections in the cohort, and 2) a cross-sectional study of STDs diagnosed in the non-PH facilities of Wilson County during a two-month period (n=400) to provide a complete picture of STDs in the entire county. Based on information obtained in the ethnography and epidemiological components, a program using peer opinion leaders to convey information and attitudes to high risk groups will be implemented and evaluated for its efficacy in changing behaviors and perceived norms of risk-reducing behaviors. The study will thus provide comprehensive information on three STDs, their determinants, and aspects of their preventability for the complete population of a rural county.